1. Field of the Invention
This invention relates to internally cooled windings and parallel phase lead rings of dynamoelectric machines, and more particularly, to means for electrically connecting stator coils to parallel phase lead rings.
2. Description of the Prior Art
Increased efficiency and economies of scale have historically resulted in demands for turbine generators of ever increasing rating. Such rating increases have, however, been accompanied by demands for maintenance of or even reduction in the physical size of the machines. Accomplishing such polarized objectives sometimes necessitated the use of liquid cooling in the turbine generator's stator coils. Parallel phase rings which provide electrical communication to the machine's external bushings have usually been cooled with gaseous coolant. However, the size limitations imposed on increasingly higher rated machines sometimes requires liquid cooling of the parallel phase rings. Phase leads provide electrical communication between the parallel rings and terminating portions of the stator coils. In the past flexible phase leads have been utilized to compensate for assembly misalignments between the phase lead connection points on the parallel phase rings and stator coils. It has been found, however, that flexible phase leads can have natural frequencies less than desired. Such natural frequencies can render the phase lead components vulnerable to excessive vibration and stress. Short, stiff phase leads with relatively high natural frequencies were thought to be unable to accomodate misalignment between the parallel phase rings and stator coils. Adequate sealing for liquid coolant flow through the phase leads provided an additional obstacle to liquid cooled phase leads. Such coolant sealing was not previously of great import since the gaseous coolant which formerly customarily cooled the phase leads would not contaminate or harm the generator's interior.
Thus, liquid cooling or stiff phase leads which would accommodate misalignments between the parallel phase rings and stator coils was desirable, but were believed difficult objectives to simultaneously attain.